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We give a model-theoretic characterization of the class of geometric theories classified by an atomic topos having enough points; in particular, we show that every complete geometric theory classified by an atomic topos is countably…

Category Theory · Mathematics 2013-04-26 Olivia Caramello

We establish an integration theory for singular subalgebroids, by diffeological groupoids. To do so, we single out a class of diffeological groupoids satisfying specific properties, and we introduce a differentiation-integration procedure…

Differential Geometry · Mathematics 2025-10-23 Iakovos Androulidakis , Marco Zambon

We provide a formulation of the univalence axiom in a universe category model of dependent type theory that is convenient to verify in homotopy-theoretic settings. We further develop a strengthening of the univalence axiom, called pointed…

Logic in Computer Science · Computer Science 2025-12-19 Chris Kapulkin , Yufeng Li

We propose foundations for a synthetic theory of $(\infty,1)$-categories within homotopy type theory. We axiomatize a directed interval type, then define higher simplices from it and use them to probe the internal categorical structures of…

Category Theory · Mathematics 2023-06-09 Emily Riehl , Michael Shulman

We introduce a notion of equivalence on tilings which is formulated in terms of their local structure. We compare it with the known concept of locally deriving one tiling from another and show that two tilings of finite type are…

Condensed Matter · Physics 2009-10-28 Johannes Kellendonk

We explore the concept of conjugation between subgroupoids, providing several characterizations of the conjugacy relation (Theorem A in {\S}1.2). We show that two finite groupoid-sets, over a locally strongly finite groupoid, are…

Group Theory · Mathematics 2021-06-29 Laiachi El Kaoutit , Leonardo Spinosa

We develop algebraic models of simple type theories, laying out a framework that extends universal algebra to incorporate both algebraic sorting and variable binding. Examples of simple type theories include the unityped and simply-typed…

Logic in Computer Science · Computer Science 2020-07-01 Nathanael Arkor , Marcelo Fiore

We exhibit a computational type theory which combines the higher-dimensional structure of cartesian cubical type theory with the internal parametricity primitives of parametric type theory, drawing out the similarities and distinctions…

Logic in Computer Science · Computer Science 2019-07-10 Evan Cavallo , Robert Harper

In this paper, we give an accessible introduction to the theory of orbispaces via groupoids. We define a certain class of topological groupoids, which we call orbigroupoids. Each orbigroupoid represents an orbispace, but just as with…

Category Theory · Mathematics 2014-01-21 Vesta Coufal , Dorette Pronk , Carmen Rovi , Laura Scull , Courtney Thatcher

Orthogonality in model theory captures the idea of absence of non-trivial interactions between definable sets. We introduce a somewhat opposite notion of cohesiveness, capturing the idea of interaction among all parts of a given definable…

Logic · Mathematics 2024-11-20 Alessandro Berarducci , Pantelis E. Eleftheriou , Marcello Mamino

The aim of this paper is to present a simplified version of the notion of $\infty$-groupoid developed by Grothendieck in "Pursuing Stacks" and to introduce a definition of $\infty$-categories inspired by Grothendieck's approach.

Category Theory · Mathematics 2010-09-14 Georges Maltsiniotis

In this paper, we explore a connection between type universes and memory allocation. Type universe hierarchies are used in dependent type theories to ensure consistency, by forbidding a type from quantifying over all types. Instead, the…

Programming Languages · Computer Science 2024-07-10 Paulette Koronkevich , William J. Bowman

Homotopy type theory is an interpretation of Martin-L\"of's constructive type theory into abstract homotopy theory. There results a link between constructive mathematics and algebraic topology, providing topological semantics for…

Logic · Mathematics 2023-03-31 Steve Awodey , Nicola Gambino , Kristina Sojakova

Groups of finite type (also called finitely constrained groups), introduced by Grigorchuk, are known to be the closure of regular branch groups. This article explores many of their properties. Firstly, we prove that being finitely…

Group Theory · Mathematics 2025-09-05 Santiago Radi

We give sufficient conditions for the existence of a model structure on operads in an arbitrary symmetric monoidal model category. General invariance properties for homotopy algebras over operads are deduced.

Algebraic Topology · Mathematics 2009-09-29 Clemens Berger , Ieke Moerdijk

A groupoid $\Omega \left( \mathcal{B} \right)$ called material groupoid is naturally associated to any simple body $\mathcal{B}$. The material distribution is introduced due to the (possible) lack of differentiability of the material…

Mathematical Physics · Physics 2018-12-18 V. M. Jiménez , M. de León , M. Epstein

We introduce the notion of wide representation of an inverse semigroup and prove that with a suitably defined topology there is a space of germs of such a representation which has the structure of an etale groupoid. This gives an elegant…

General Topology · Mathematics 2012-04-03 Dmitry Matsnev , Pedro Resende

Universal algebra uniformly captures various algebraic structures, by expressing them as equational theories or abstract clones. The ubiquity of algebraic structures in mathematics and related fields has given rise to several variants of…

Category Theory · Mathematics 2019-03-19 Soichiro Fujii

Inductive and coinductive types are commonly construed as ontological (Church-style) types, denoting canonical data-sets such as natural numbers, lists, and streams. For various purposes, notably the study of programs in the context of…

Logic in Computer Science · Computer Science 2015-07-01 Daniel M Leivant

The fundamental bigroupoid of a topological space is one way of capturing its homotopy 2-type. When the space is semilocally 2-connected, one can lift the construction to a bigroupoid internal to the category of topological spaces, as Brown…

Algebraic Topology · Mathematics 2018-02-02 David Michael Roberts